The present invention relates to apparatus for manipulating elongated flexible webs, particularly for reducing and/or equalizing localized stresses in running webs consisting of paper, imitation cork, reconstituted tobacco, lightweight cardboard, synthetic plastic materials or the like. Still more particularly, the invention relates to apparatus for manipulating running webs in filter cigarette making or like machines wherein a web is coated with adhesive at one of its sides and convoluted around rod-like tobacco filters, filter rod sections and/or plain cigarettes, cigarillos or cigars, for example to form filter cigarettes, cigarillos or cigars of unit length or multiple unit length.
A web of relatively still paper, imitation cork or like flexible material is normally treated by a so-called curling device (often called curling bar) prior to draping around filter material and/or wrapped or unwrapped rod-like tobacco filters. The purpose of the curling device is to reduce localized stresses and/or to reduce or eliminate differences in the length of longitudinally extending strip-shaped portions of webs. Reference may be had to the aforementioned copending application Ser. No. 504,757 which describes conventional (fixedly mounted) as well as several novel (movable or yieldable) curling devices and the manner in which such curling devices contribute to reduction or elimination of localized stresses and/or differences in length of longitudinally extending portions of webs made of paper, imitation cork or the like. The curling device also serves to reduce the stiffness of the running web so that the latter can be readily coiled around a rod-like filler or around two or more wrapped rod-shaped article. The curling device employs a relatively sharp elongated web-contacting or web-engaging member which bears against one side of the running web and flexes successive increments of the web, preferably before the thus treated side is coated with adhesive paste. The flexing and resulting softening of running web is desirable because such web can be readily converted into a tube which sealingly surrounds the joint between a filter rod section of unit length and a plain cigarette, cigar or cigarillo of unit length of between a filter rod section of double unit length and two plain cigarettes, cigars or cagarillos of unit length, depending upon whether the machine is to produce filter cigarettes, cigars or cigarillos of unit length or multiple unit length. However, proper flexing and curling of the web is insured only if the web bears against the curlng device with a certain force which is likely to result in damage to (particularly breaking or tearing of) the web during acceleration of the web and/or when a weakened or defective portion of the web travels past the web-contacting member of the curling device. Such weakened or defective portions of webs include splices which are used to connect the trailing portion of an expiring web to the leader of a fresh web as well as web portions which are weak due to malfunction of the machine which makes the web.